Grosbeak Creek: Use of Bioengineering Techniques in the Restoration of an Agricultural Ditch at 1020 Beckwith Avenue, Saanich, B.C.

Abstract

A functioning riparian zone surrounding an ephemeral stream is the result of transforming thirty-five meters of an agricultural drainage ditch using bioengineering techniques. The owners of the property where Grosbeak Creek is located are interested in the beautification and recreation potential a treed corridor will bring. Increasing biodiversity richness is also important. Characteristics of riparian habitats are more abundant in biodiversity than adjacent ecosystems, these characteristics create a matchless environment that is multifaceted and irreplaceable, delivering distinct utilities not found in other ecosystems. Plants that have the ability to tolerate their roots being submerged during the wet season are foundational to riparian communities. Their roots retain soils; branches provide shade cooling water temperatures for fish. These zones are nurseries for animals whose lifecycle include an aquatic phase.
In winter 2016 the agricultural ditch at 1020 Beckwith Avenue was excavated to have bends and curves in order to dissipate flashy storm water events. The banks were widened to decrease the pitch making it more accessible. Logs, boulders and coarse woody debris (CWD) were added to protect the banks from erosion. The site was staked with Sitka Willow (Salix sithensis), Pacific Willow (Salix lucida ssp. lasiandra), Hooker’s Willow (Salix hookeriana), Red Oiser Dogwood (Cornus stolonifera) and Cottonwood (Populus trichocarpa) because the genus Salix is known for the ability to quickly root from cuttings. A covering of wood chips was spread over the site to reduce weeds from germinating, keep moisture in the ground and to provide habitat for mycorrhizal spores to invade building filament structure supporting the entire ecosystem community. Restoring ecological function by building riparian woodland will benefit biodiversity.